Computed tomographic method

Abstract

In a computed tomographic method in which a tomographic image of an object is composed from many X-ray projection distribution images obtained by exposing a section of the object to X-rays in many different directions, the X-ray projection distribution images obtained by respective exposures to X-rays are once stored at positions different from one another on a stimulable phosphor sheet, the stimulable phosphor sheet is then scanned with a stimulating ray, and a tomographic image of the object is composed by use of electric signals obtained by photoelectrically reading out light emitted from the stimulable phosphor sheet upon stimulation thereof. The stimulable phosphor sheet and an X-ray source are integrally rotated around the object, while the stimulable phosphor sheet is moved approximately at right angles to the plane formed by the rotation thereof.

I claim: 
     
       1. A computed tomographic method in which a tomographic image of an object is composed from a plurality of X-ray projection distribution images obtained by exposing a section of the object to X-rays in a plurality of different directions, wherein the improvement comprises once storing the X-ray projection distribution images obtained by respective exposures to X-rays at positions different from one another on a stimulable phosphor sheet, scanning said stimulable phosphor sheet with a stimulating ray, and thereafter composing a tomographic image of the object by use of electric signals obtained by photoelectrically reading out light emitted from said stimulable phosphor sheet upon stimulation thereof. 
     
     
       2. A method as defined in claim 1 wherein said stimulable phosphor sheet is provided with a layer of a stimulable phosphor emitting light having a wavelength within the range between 300nm and 500nm upon stimulation thereof. 
     
     
       3. A method as defined in claim 1 wherein said stimulating ray has a wavelength within the range between 600nm and 700nm. 
     
     
       4. A method as defined in claim 1 wherein said X-rays are applied from an X-ray source in a fan-like form spreading at an angle in the range between about 30° and 40°. 
     
     
       5. A method as defined in claim 1 wherein said stimulable phosphor sheet is positioned to form an arc at an equal distance from an X-ray source. 
     
     
       6. A method as defined in claim 1 wherein said stimulable phosphor sheet and an X-ray source are integrally rotated around the object. 
     
     
       7. A method as defined in claim 6 wherein said stimulable phosphor sheet is also moved approximately at right angles to the plane formed by the rotation of said stimulable phosphor sheet and said X-ray source.